Typically, optical modules house optical components hermetically in a box, such as in a so-called "14-pin butterfly" housing or package. For example, laser modules used in lightwave transmission systems include a semiconductor laser configured to emit coherent radiation for communication purposes. Although the laser resonates over a range of frequencies, the laser is typically confined to operate at, or is so-called "locked" to a single desired wavelength, even with variations in temperature, such as by using an external fiber grating. This locking mechanism, however, only works over a particular range in temperatures.
Accordingly, such laser modules are specifically manufactured so that the laser properly locks over the span in temperatures for the desired application. That is, the laser's so-called "locking range" is nominally designed to match the desired operating temperature range. Unfortunately, for various manufacturing reasons, the laser's locking temperature range may not match the span in temperatures for the desired application. Although the laser's temperature can be maintained to fall within its locking range using thermal electric coolers (TECs) or resistive heaters, it may not be practical to do so for certain applications because of reliability and maintenance considerations, such as for so-called "submarine" applications.
In the prior art, the prevailing wisdom is either to discard or rework the laser module, which in either case is usually cost prohibitive. It would therefore be desirable to provide for an improved laser module wherein its operating temperature range is readily adjustable so as to substantially cover or be coextensive with the span in temperatures for the desired application.